A treatise on zoology . of the Diploporita, although abranch parallel with the Mesocystidae passes onin the direction of the Eublastoidea, beyond theboundary of the Cystidea. Genera—Mesocystis,Bather (Jan. 1898, =Mesites, Hoffmann, 1866;Nikitin, 1877 ; Agelacrinus, Schmidt, 1874),Ordovician, Esthonia. Theca (Fig. XLVII. 1)simulates that of a regular echinoid, or still more, ^^^^Eclrioaster, since the mouth is on the uppersurface; from it narrow food-grooves, protectedby covering-plates, pass straight down to the ^^^- ^^^i- margin of the flattened aboral surface (Fig. , Proterobiasty^ showing ^
A treatise on zoology . of the Diploporita, although abranch parallel with the Mesocystidae passes onin the direction of the Eublastoidea, beyond theboundary of the Cystidea. Genera—Mesocystis,Bather (Jan. 1898, =Mesites, Hoffmann, 1866;Nikitin, 1877 ; Agelacrinus, Schmidt, 1874),Ordovician, Esthonia. Theca (Fig. XLVII. 1)simulates that of a regular echinoid, or still more, ^^^^Eclrioaster, since the mouth is on the uppersurface; from it narrow food-grooves, protectedby covering-plates, pass straight down to the ^^^- ^^^i- margin of the flattened aboral surface (Fig. , Proterobiasty^ showing ^ ^ A 1 1 1 V o brachioles (Br), food-grooves XLVII. 2). Adambulacrals raised above the (Ami) bordered by adambu-general surface of the theca, by the pushing in JSlr After Sd!under them of the adjacent interambulacrals; thus they outwardly resemble the sub-ambulacrals or side-plates ofCallocystinae (Fig. XLVII. 3). The interambulacrals do not, however,absolutely meet underneath the adambulacrals, but leave an irregular. 76 THE CYSTIDEA canal (which may have contained a nerve of the aboral nerve-system).Interambulacrals numerous and irregular, all pierced by lies in a depression (cf. Edrioaster) ; surrounded by five interradial,slightly forked A, apparently continuous with the adambulacrals, andhomologous with the five plates similarly situated in Spliaeronis. Posterior M--.
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
